Washing and after-treatment of yarn



Oct. 13, 1936.

J. L. BITTER I wAsHI NG AND AFTER TREATMENT OF YARN Aon' L. 5/7758 COOS 0 0 Q o o 0 0 0 0 O O 0 Q o o 0 e 0 0 o o o o 0 Filed Feb. 14, 1935 Patented Oct. 13, 1936 WASHING 'AND AFTER-TREATMENT A N Jack L.,Bitter, ElizabethtoniTenns,assignor to North American Rayon' Corporation,

New

York, N. Y., a' corporation of Delaware 7 V Application February 14,- 1935,:Serial No. 6,502

3 Claims.

The present invention relates to an improvement in the manufacture of yarn of artificial origin, but more specifically has for its object to provide a novel process for use in the washing of freshly-spun yarn bodies.

Another object of the-present invention is to provide a method whereby a uniform yet slow 20 illustrated a cross-sectional view of one form of apparatus which may be used to carry out the new method comprising my invention.

In the previous application Serial Number 6,503 filed on Feb. 14, 1935, I have set forth a method of 25 washing of artificial yarn whereby, first of all, a spinning solution is used, and then the solution is gradually diluted with water until pure water alone is employed. The present invention might, in a certain sense, be said to be an improvement 30 over the former process because the same results are here accomplished in a more expedient and. economical way.

My novel method is also a decided improvement over a certain known process which consists 35 of subjecting the artificial silk to an electric current. This isdone by inserting electrodesinto solutions which are separated by a diaphragm, the cellulose product being immersed in one of the solutions. The process is used only for the 40 residues which might be retained in the yarn body. This method, however, is only used at the end of the washing process, and further, when used, is somewhat drastic in its effect on the yarn. While the process does remove any resid- 45 ual salts which may be left in the yarn body,

the dyeing effect of the finished filaments remains unimproved, due to the accelerated speed of the process and the use of ordinary washing methods for the major portion of the washing step prior to the electrical treatment.

It is therefore the purpose of the present invention to remove all chemicals from the freshlyspun yarn by a method which will affect the fila- 55 ments least.

Inthe drawing is shown a container or tank ('2) having an inlet or supply pipe (3) through which the washing solution is passed and a drain pipe (4). For purposes of illustration, I have shown only two spools, (I) and (I') placed with- 5 'in the tank (2) One-of the spools is shown in cross-section; wherea s,the otheris shown in side elevation. In both cases, however, the y'arnbodies are shown in section, the better to set forth my invention.

The yarn bodies on the spools l and l are indicated at 5. The spools I and l' and the yarn bodies 5 wound thereon are those usual in the art.

Surrounding the yarn bodies are diaphragms (6) through which both the solutions used may pass.

In operation of my method the spools l and I', with the filament bodies mounted thereon, are placed on end in the tank (2) and within the 2 diaphragm (6). The diaphragm (6), by separating or enclosing the various spools, also provide a space between the diaphragms (6) and the thread bodies (5), which is filled with a spin bath solution (S), or one which is of similar chemical nature.

The interior of the spools, as is shown with relation to spool I, is also filled with this solution. Outside the diaphragms (6), water is continually circulated in the tank (2) by passing it from the supply pipe (3) and then passing it out the drain (4). This washing liquid is indicated at W.

As will be seen from the sketch, a newly-spun yarn, impregnated with the spinning bath solution, is here placed so as to be contacted on all sides by some of the same solution used in the coagulating or spinning bath. Water flows on the other side of the permeable membrane or diaphragms (6) and because of the differences in osmotic pressures between the two solutions 5 and W, the water tends to pass inwardly toward the spools (see arrow a) and the bath chemicals outwardly from the spool (arrow b) It may be seen that the spinning solution is continually passing off into the water. In connection with the spool I, I have shown two arrows (a and b) which depict the manner in which the spinning bath solution within the spool gradually tends to merge with that outside the spool, the outside solution continually passing off into the water. Continual washing is thus accomplished and finally the space within and about the spools formerly occupied by the bath solution is occupied only by the water.

When this point is reached the yarn will be found to have been completely and gradually washed free of all chemicals in such a manner that no portion of the yarn is washed more quickly than any other portion.

I have found that yarn produced in this manner possesses very much improved dyeing qualities and the unevenness of dyeing which hitherto has been of such a disadvantage in finished fabrics can be practically totally eliminated.

My invention may be also employed in respect to cakes of yarn prepared by the spinning pot or centrifugal method, in which case the cakes may be placed in the same position-as the spools, I and l, and the spinning solution provided both within and without the cake as in the case of the spools. If the cakes are so wound that no support is necessary they may be placed in the washing container just as they are removed from the pot, however, if desired, a perforated or foraminous support of some kind may be inserted within the cakes by any of the wellknown methods.

My process may be employed in any wet spinning process where a bath is used and in each case the letter S indicates that the solution used is of approximately the same chemical composition as the bath employed in the process.

Having now set forth my invention as required by the patent statutes, what I desire to claim is:

1. In a method for simultaneously freeing all portions of a wet spun yarn body from bath liquids, the step of placing the yarn bodies, surrounded by and containing within their inner surfaces a liquid chemically identical to the bath, Within a permeable diaphragm, and then continuously passing washing liquid around the outer surface of said diaphragm until, by osmosis, the liquid within the diaphragm is dispersed into said washing liquid.

2. In the washing or purification of wet spun yarn bodies, the steps of surrounding the bodies, inside and out, with the bath liquid, and then gradually displacing the said bath liquid with a washing fluid employing osmotic pressure to accomplish this displacement.

3. In a device for evenly and simultaneously washing bath chemicals from a wet-spun yarn body, in combination, a series of yarn bodies embraced by a series of permeable diaphragms, means to ,fill the interior of said diaphragms with bath liquid so that the inner and the outer surface of said bodies contact said bath liquid, and means for circulating a washing fluid around the outside of the various diaphragms.

JACK L. BITTER. 

